RESEARCH MEMORANDPM. I\OBbRY '3

Transcription

1 - o RESEARCH MEMORANDPM \OBbRY '3 i

2 NATONAL ADVSORY COMMJTTEX FOR AEXONAUTCS RESEARCH MEMORANDUM FRST LAMDNG By Richard E. OF BEXG X-2 RESEAR-&l ARPLANE Day and Wendell H. Stillwell The Bell X-2 supersonic research equipped with a skid main landing gear and a nose wheel. Pending canrpletion of the rocket engize, glide flights axe being performed to determine low-speed handling qualities of the airplane and the landing characteristics with the skidtype landis gear. The present paper presents data obtained during the approach and landing of the X-2 airplane on its Pirst flfght. n The approach speed was about 215 dies per hour and touchdown wa6 made at 142 miles per hour, idicated airspeed, with a normal-force coefficient of bed the skid the airplane pitched down and the nose-wheel, decderation during most H- of the ground run was between 0.k and 0.8g. The total distance of the ground run was 1,010 feet. 1 pt-.' rnou(=ton 7 4 The Bell X-2 supersonic research airplane has been constructed E&$,%% 'L part of the joint. Air Force - Navy - National Advisory Committee for Aeronautics high-speed flight research program. The X-2 airplane is intended to investigate the characteristics of swept-wing &?planes at hlgh supersonic speeds. The airplane has.several _unconventional features among which are the circular-arc wing section profile and the skid-type landing gear. Pending the completion of the rocket engine far the X-2 airplane, glide flights are being performed by the Bell AircYaft Corp. These fllghts are for the purpose of determinfng the landing characteristics and flight-characteristics at low speeds. The first- glide flight was performed June 27, The airplane was launched from the Being B-50 mother airplane at an altitude of 31,500 feet and made a 9-minute flight terminated by a landing on the dry lake bed.'

3 2 w NACA RM ~521~. The purpose of the present paper is to document the approach and landing data of the fir& flight. Other data recorded during the flight are now being analyzed. SYMBOLS pressure altitude, ft indicated airspeed, elevator deflection, mph deg total aileron deflection, deg rudder deflection, deg elevator force, aileron force, lb lb no"l"gcekratfon, g units Longitudinal acceleration, g units lateral acceleration, g units pitching angular velocity, radians/sec rolling a- velocity, ra&ans/sec yawing angular velocity, rat~ans/sec - angle of attack, deg - - angle of sideslip, deg acceleration due to gravity, ft/sec2 ARPLANE AND NSTRUMENTATON The X-2 airplane is a low-wing single-place research airplane having bo sweep of the quarter chord and O-percent-thick circular-arc airfoil sections normal to the quarter chord. For the fllght reported herein the rocket motor was not installed. The geometric characteristics of the

4 NACA RM ~ ~ c., airplane are prese te in ble and a sketch-of the airplane is shown as figure 1. The F&&?&&%d~46!&lected 15a for the entire flight. / The landing gear of this airplane coneists of a main landing skid, nose wheel, and wing-tip skids. A drawing of the landing-gem arrangement is presented as figure 2 and a photograph-of the airplane in the normal ground attitude is shown as figure 3. The airplane was instrumented to record the following quantities on internal recording instruments: Altitude Airspeed Normal, transverse, and longitudinal acceleration Rolling angular velocity Pitching angular velocity Yawing angular velocity Elevator angle Aileron angle Stabilizer angle Rudder angle Flap angles, Elevator stick force. Aileron stick force Sideslip angle Angle of attack The accelerometer is located 123 inches gravity of the airplane. " foiward of the center of n addition to the internal inetrumentation, a modified S(=R 584 radar - set was employed to obtain the airplane flight path and Landing trajectory- All instrumentation waa synchronized by a common timer. TESTS, RESULTS, AND DSCUSSON c The landing approach pattern as recorded by- radar is shown in figure 4. The winds at the ground level were about-5 miles per hour and were from the south-southwest. The approach wasstarted on the downwind leg opposite the touchdown point at geametric altitude of 6,500 feet and indicated airspeed of 223 miles per hour with trailing-edge flaps up. The speed was approximately 220 milea per hour, indicated airspeed, during the downwind and base legs. The trai1ing:edge flaps were lowered 28O at 210 miles per huur and an altitude of 1,000 feet in the final approach. The flight path was not obtained belo4 an altitude of 200 feet because of interve-hing obstacles.

5 ! s i! Time histories of the measured quantities during the flaps-down portion of the approach and landing are shown-in flgure 5. The speed in the approach was reduced gradually from 206 miles per hour at time zero to 183 miles per hour at time 26 seconds. After time 26 seconds the speed decreased more rapidly as the pilot held the airplane off until the contact occurred at indicated airspeed of 142 miles per hour and with a normal-force coefficient of ntegration of the accelerometer records indicated that vertical velocities were less than 5 feet per second near and at touchdown. t was expected that the pilot would be able to control the pitching at contact. However, the pitching at touchdown was uncontrollable and the airplane experienced a peak longitudinal deceleration, exceeding the range of the recorder. The airplane developed a maximum pitching velocity of radian per second resulting in about a 3.8g acceleration on the nose gear at contact. The airplane slid along on the main skid and nose %?keel leaving a track the width of the skid and approximatdy 121 inches deep in the lake bed. A sketch of the skid marks on the lake is shown figure 6. At time 39.5 seconds the pilot. applied left aileron con$rol causing tlie airplane to roll to the left and-deapite corrective aileron control applied time 41.5 seconds, tbileft wing tip contacted the ground at the point 764 feet from touchdown. This contact was carnatively light but the drag on the tip yawed the airplane about 14O. The right wing-tip skid then etruck the ground heavily and broke off. The afrplane yawed about 35' to the right and the left tip contacted again. The left skid was bent inward at this impact and the leading edge.of the wing dug into the lake bed and the airplane came to a stop, The total distance covered on nspection of the nose wheel revealed that ing the landing. t wm. indicated from f yaw vane found on the lake bed aiii From comments of the chase pilot that the ROS~ wheel collapsed irnmedfately after ground contact. Ffgure 7 is a photograph of the skid marks OR the lake and the final resting position of the airplane. The marks made by the wlng-tip ekids are clearly visible in the photograph. at Langley Aeronautical Laboratory, National Advi eory Committee for Aer~gau-~ic_s,-- Langley Field, V a., e G F z% /PgL2..".. Apprmed: Engineer - Rartl. Soul&+ Ass is tant - vr - m Richard E. Day Aeronautical Research Scfentist Wendell H. Stillwell Aeronautical

6 NACA RM L52ll 5 wing: TABLE 1. PEYSCALCBARACTERSTCS OF X2 ARPLANE Area. sq ft Span. ft Aspect ratio Taper ratio Sweep at 0.25 chord. deg Airfoil section... O-percent-thick circular-arc ncidence: Root. deg... Tip. deg... Dihedral. deg... Aileron: Area. sq ft... Travel. deg... Area (total). sq ft.. Travel. deg... Flap. trailing edge: Flap. leading edge: Area (total). sq ft.. Travel. deg... Horizontal tail:.l Area. sq ft... Span. ft... Aspect ratio... Sweep at 0.25 chord. deg. Airfoil section... Elevator: Area. sq f t... Travel: up. deg... Down. deg... Stabilizer: Travel : Leading edge up. deg. Leading edge down. deg " : NACA L 10..

7 6 TABLE. - Concluded PHYSCAL CEABACTERSTCS OF BELL X12 ARPWJE Vertical tail: Area, excluding dorsal, sq ft Sweep of leading edge, deg Airfoil section: Root... NACA Tip NACA Fuselage : Length, ft Fineness ratio Airplane weight, lb... 10,337 Center-of-gravity location, percent M.A.C

8 NACA 3 Figure 1.- Three-view drawing of the Bell X-2 research airplane. dimensions are in inches. A 11

9 c Y Figure 2.- Drawing ahowing the landing-skid and nose-wheel installatlon on the Bell X-2 resemch airplane.

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11 10 NACA RM LyU Figure 4.- Landfng approach pattern of the Bell X-2 research ahplane.

12 NACA RM L52ll Time, t, 5e3c Figure 3. - The history of landin@; of Bell X-2 research airplane. Stabilizer setting, 2.2O leading edge d m; wi%ight, 10,337 pounds.

13 fa- NACA RM L5ZSU t " /B /8 ZO E2 24 LQ Z Fms, f, scc Figure 5.- Continued.

14 NACA RM L521l-l - 1 i fin?&, * JG Figure 5. - Concluded. "

15 ! Figure 6. - Ground path of the Bell X-2 research airplane...

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17 ~ Operating Sub.l ec t.-. Airplanes Specific m a <-. Amlanes - Performance.. LControl, Longitudinal -.Flying Qualities,,Loads, Landing ~mpact, una ~,L,oade, Landing - Ground-Run, Land Problems, General number Landing data of the first glide flight of lie skid-equipped Bell X-2 research airplane are presented. b c